It is known from published International Patent application WO8806722A, to use a half spherical blade which rotates about an axis to provide a cutting action and the half spherical blade is articulated about an axis such that the blade follows an arcuate path to cut and separate a sample from the surface of a component.
It is also known from our prior UK Patent application GB2282778A to use a part spherical blade which reciprocates about an axis to provide a cutting action and the part spherical blade is moved through an arcuate path to cut a sample from the surface of a component.